This is not unlimited
This is not unlimited, unless by that you mean reading a limited selection of books from their overall catalogue that they predetermine while losing access to books you actually want to read with no notice and no clear idea of what criteria they're using.
As it is, I lost access to books I'm using for research, leaving me with no choice but to find them elsewhere. Thankfully, Perlego seems to be genuinely unlimited.
Reply from Scribd
Hi David, we apologize for any confusion with your Scribd membership. You'll notice the library catalog rotates as you read. While some titles may not be immediately available, there will always be something you can read! Since we all use Scribd differently, we'd be happy to take a closer look here and be able to provide more personalized, specific context on your experience. Feel free to submit a ticket through this link to connect directly with our support team: https://scr.bi/assist